Vehicle occupant protection device

ABSTRACT

A vehicle occupant protection device includes an airbag constructed as an integrated bag body that is deployable in an area including a front side of a head portion of a vehicle occupant, and in an area including both left and right sides of the head portion of the vehicle occupant, and an airbag case. The airbag case includes a box-shaped case main body provided on a seat rear side of a headrest main body, in which the airbag is housed in a folded state, and that inflates and deploys the airbag from an upper portion of the case main body during an inflation and deployment of the airbag, and a reaction force plate that is provided in a lower portion side of the case main body and inside the case main body, and that supports the airbag from the seat rear side during the inflation and deployment of the airbag.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/286,172, filed Oct. 5, 2016, and is based on and claims priorityunder 35 U.S.C. § 119 from Japanese Patent Application No. 2015-237979,filed on Dec. 4, 2015. The entire contents of each of the aboveapplications are incorporated by reference herein in entirety.

BACKGROUND Technical Field

The present invention relates to a vehicle occupant protection device.

Related Art

An airbag device is known (see Japanese Patent Application Laid-Open(JP-A) No. 2000-344044) that, in the event of a collision, supplies gasfrom an inflator through a gas supply pipe that is fixed to a seat backto a bag that is attached to the gas supply pipe, and causes this bag toinflate so as to cover a front and sides of a head portion of a vehicleoccupant. In addition, an airbag device is known (see JP-A No.2013-018378) in which an airbag for a head portion is deployed towardsthe front at left and right end portions of a seat headrest, and thesejoin together at the front surface of the vehicle occupant head portion,while an auxiliary airbag for a head portion is deployed towards thefront from a central portion of the seat headrest so as to join with thepair of head portion airbags. In addition to these, a structure in whichan airbag that inflates so as to cover the front and sides of the headportion of a vehicle occupant is housed in a seat back is disclosed inGerman Patent Application Publication No. 19859988A1.

In the structure disclosed in JP-A No. 2000-344044, because the gassupply pipe is provided such that it protrudes above the seat back, ithas an unattractive appearance and the gas supply pipe is an obstructionwhen the vehicle seat is being operated.

On the other hand, in the structure disclosed in JP-A No. 2013-018378,it is difficult to guarantee a satisfactory mutual join strength betweenthe pair of head portion airbags that are joined together after beinginflated and deployed, or a satisfactory join strength when theauxiliary head portion airbag is joined to the pair of head portionairbags.

As a measure to counter such drawbacks, consideration may be given toemploying a structure in which an airbag that is formed as an integratedbag body is housed in a rearward side of a headrest main body, and thisairbag is inflated and deployed so as to cover the head portion of avehicle occupant from the front and from both the left and right sides.However, because the headrest main body is disposed in front of theairbag, there is a possibility that it will be difficult to make theairbag inflate and deploy on the seat front side, and the airbag will bebadly obstructed by the head portion of the vehicle occupant or thevehicle cabin ceiling or the like when it passes over the headrest mainbody and the head portion of the vehicle occupant. Because of this,there is room for improvement from the standpoint of improving thedeployment performance of the airbag.

SUMMARY

In consideration of the above-described circumstances, it is an objectof the present invention to provide a vehicle occupant protection devicethat, in a structure in which an airbag which is constructed as anintegrated bag body is housed in a folded state in rearward side of aheadrest main body, makes it possible to improve the deploymentperformance of the airbag.

A vehicle occupant protection device according to a first aspect of thepresent invention includes an airbag that is inflated and deployed uponbeing supplied with gas, and that is constructed as an integrated bagbody that is deployed in an area that includes a front side of a headportion of a vehicle occupant, and in an area that incudes both left andright sides of the head portion of the vehicle occupant so as to coverthe head portion, and also includes an airbag case that is constructedso as to include a box-shaped case main body that is provided on a seatrear side of a headrest main body which supports the head portion fromthe rear, and in which the airbag is housed in a folded state, and thatis formed from resin, and whose upper portion opens up during aninflation and deployment of the airbag, and so as to include a reactionforce plate that is provided in a lower portion side of the case mainbody, and is formed by a component having greater rigidity than the casemain body, and that supports the airbag from the seat rear side duringthe inflation and deployment of the airbag.

In the vehicle occupant protection device according to the first aspectof the present invention, an airbag case is provided on the seat rearside of the headrest main body, and an airbag is housed in a foldedstate inside this airbag case. Here, the airbag is constructed as anintegrated bag body that is deployed in an area that includes a frontside of a head portion of a vehicle occupant, and in an area thatincudes both left and right sides of the head portion of the vehicleoccupant so as to cover the head portion, and inflates and deploys uponbeing supplied with gas. As a consequence, the head portion of thevehicle occupant is restrained and protected by the airbag in variousdifferent types of collision.

Moreover, the airbag case is provided with a box-shaped case main bodythat is formed from resin, and this case main body is formed such thatan upper portion thereof is opened up when the airbag is inflated anddeployed. In addition, a reaction plate that is formed by a componenthaving greater rigidity than the case main body is provided in the lowerportion side of the case main body, and the airbag is supported from theseat rear side by this reaction force plate when the airbag is beinginflated and deployed. As a consequence, reaction force towards the seatfront side is applied from the reaction force plate to the airbag, andit becomes easy to make the airbag inflate and deploy towards the seatfront side from the upper portion of the case main body.

A vehicle occupant protection device according to a second aspect of thepresent invention is characterized in that, in the structure accordingto the first aspect, the reaction force plate is provided with a rearwall reinforcement portion that is disposed in parallel with a rear wallof the case main body, and side wall reinforcement portions that extendtowards the seat front side in parallel with side walls of the case mainbody from both sides in the seat transverse direction of the rear wallreinforcement portion, and seat front sides of the side wallreinforcement portions either slope or are curved such that, when viewedfrom the seat transverse direction, a lower portion of each side wallreinforcement portion is located closer to the seat front side than anupper portion of each side wall reinforcement portion.

In the vehicle occupant protection device according to the second aspectof the present invention, during the inflation and deployment of theairbag, reaction force towards the seat front side is applied to theairbag from the rear wall reinforcement portion that is disposed inparallel with a rear wall of the case main body. Here, side wallreinforcement portions extend towards the seat front side in parallelwith side walls of the case main body from both sides in the seattransverse direction of the rear wall reinforcement portion. As aconsequence, compared with a structure in which the side wallreinforcement portions are not provided, it is possible to increase therigidity of the reaction force plate, and to increase the reaction forcethat is applied to the airbag.

Moreover, the seat front sides of the side wall reinforcement portionsof the reaction force plate either slope or are curved such that, whenviewed from the seat transverse direction, a lower portion of each sidewall reinforcement portion is located closer to the seat front side thanan upper portion of each side wall reinforcement portion. As aconsequence of this, it is possible to reduce the surface area of theside wall reinforcement portions, while securing sufficient rigidity inthe lower portion of the reaction force plate, and to prevent thereaction force plate from interfering with the airbag when this isinflated and deployed in the seat transverse direction from the casemain body.

A vehicle occupant protection device according to a third aspect of thepresent invention is characterized in that, in the structure accordingto the first or second aspects, the airbag is constructed so as toinclude an outward roll-fold portion that is folded into a roll shapethat is rolled up from a front end side of the airbag when this is in adeployed state towards an outer surface side, and is housed in theairbag case in this state, and a bellows-fold portion that is foldedinto a bellows fold underneath the outward roll-fold portion, and ishoused in the airbag case in this state, wherein the outward roll-foldportion is housed in a location where, when viewed from the seattransverse direction, it does not overlap with the side wallreinforcement portions.

In the vehicle occupant protection device according to the third aspectof the present invention, when gas is supplied to the airbag, theoutward roll-fold portion is inflated and deployed towards the seatfront side over the top of the headrest main body and the vehicleoccupant as the outward roll-fold is unwound. Here, because the outwardroll-fold portion is housed in a location where, when viewed from theseat transverse direction, it does not overlap with the side wallreinforcement portions of the reaction force plate, it is possible toprevent the inflation and deployment of the outward roll-fold portionsfrom being obstructed by the side wall reinforcement portions.

As has been described above, according to the vehicle occupantprotection device according to the first aspect of the presentinvention, the excellent effect is achieved that, in a structure inwhich an airbag which is constructed as an integrated bag body is housedin a folded state in a rearward side of a headrest main body, it ispossible to improve the deployment performance of the airbag.

According to the vehicle occupant protection device according to thesecond aspect of the present invention, the excellent effect is achievedthat it is possible to cause an airbag to inflate and deploy effectivelyin a seat transverse direction at the same time as the reaction forceapplied to the airbag is increased.

According to the vehicle occupant protection device according to thethird aspect of the present invention, the excellent effect is achievedthat it is possible to cause the outward roll-fold portion to inflateand deploy towards the seat front side in such a way that it passesrapidly over a headrest main body and the head portion of a vehicleoccupant.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described indetail based on the following figures, wherein:

FIG. 1 is a side view showing in typical form an operating state of avehicle occupant protection device according to an exemplary embodiment;

FIG. 2 is a front view showing in typical form an operating state of avehicle occupant protection device according to an exemplary embodiment;

FIG. 3A is a view showing an inflated and deployed state of amulti-directional airbag that forms part of a vehicle occupantprotection device according to a first exemplary embodiment, and is across-sectional view taken along a line 3A-3A in FIG. 1;

FIG. 3B is a view showing an inflated and deployed state of amulti-directional airbag that forms part of the vehicle occupantprotection device according to the first exemplary embodiment, and is across-sectional view taken along a line 3B-3B in FIG. 1;

FIG. 4A is a side view showing the schematic overall structure prior tooperation of a vehicle occupant protection device according to anexemplary embodiment;

FIG. 4B is a front view showing the schematic overall structure prior tooperation of a vehicle occupant protection device according to anexemplary embodiment;

FIG. 5 is an enlarged perspective view showing in typical form anenlargement of a headrest according to an exemplary embodiment;

FIG. 6 is an enlarged typical side view showing in a partially cutawaystate an enlargement of a headrest according to an exemplary embodiment,and shows a state prior to an airbag being inflated and deployed; and

FIG. 7 is an enlarged typical side view showing in a partially cutawaystate an enlargement of a headrest according to an exemplary embodiment,and shows a state immediately after an airbag has been inflated anddeployed.

DETAILED DESCRIPTION

A vehicle occupant protection device 10 according to an exemplaryembodiment of the present invention will now be described based on FIG.1 through FIG. 7. Note that an arrow FR and an arrow UP that are shownwhere appropriate in the drawings respectively indicate a forwarddirection of a vehicle seat 12 (i.e., a direction in which a seatedperson faces), and an upward direction. Hereinafter, unless specificallystated otherwise, if simple front-rear, up-down, or left-rightdirections are used, then these refer respectively to the front-reardirections of the seat, the up-down directions of the seat, and theleft-right directions when facing towards the front in the seatfront-rear direction. Note also that, in this exemplary embodiment, thefront-rear direction of the vehicle seat 12 matches the front-reardirection of a vehicle, the up-down direction of the vehicle seat 12matches the up-down direction of a vehicle, and the seat transversedirection of the vehicle seat 12 matches the vehicle transversedirection. Furthermore, an arrow IN which is shown where appropriate inthe drawings shows a vehicle center side in the vehicle transversedirection of an automobile that is serving as a vehicle in which thevehicle seat 12 has been installed.

(Overall Schematic Structure of a Vehicle Occupant Protection Device)

As is shown in FIG. 1, the vehicle occupant protection device 10 ismounted in the vehicle seat 12. The vehicle seat 12 is disposed in aposition that is offset to either the left side or right side (to theleft side in the present exemplary embodiment) relative to the center inthe vehicle transverse direction of a vehicle body of an automobile (notshown in the drawings). This vehicle seat 12 is constructed so as toinclude a seat cushion 14, a seat back 16 whose bottom end is coupled toa rear end of the seat cushion 14, and a headrest 18 that is provided atan upper end of the seat back 16.

Note that, in FIG. 1 through FIG. 4B, a state is shown in which acollision test dummy D is seated on the seat cushion 14 of the vehicleseat 12 so as to serve as a model of the vehicle occupant who is to beprotected. This dummy D is, for example, a World SID (Internationallyintegrated side impact dummy: World Side Impact Dummy) AM50 (i.e., the50th percentile of American adult males). This dummy D is seated in astandard sitting posture (i.e., in a normal state) that is determinedusing a collision test method. The vehicle seat 12 is located in areference set position that corresponds to the aforementioned sittingposture. Note that a head portion H of the dummy D is a portion abovethe neck and including the face, and the face faces towards the vehiclefront side (i.e., the seat front side). Hereinafter, the dummy D will bereferred to as the ‘vehicle occupant D’ in order to simplify thedescription.

As is shown in FIG. 1 and FIG. 2, the vehicle occupant protection device10 is constructed so as to include a multidirectional airbag device 20that is intended to protect the vehicle occupant D from various types ofcollision, a side airbag device 22, and a seatbelt device 24.Hereinafter, the schematic structure of the seatbelt device 24 and theside airbag device 22 will be described, and thereafter the detailedstructure of the multidirectional airbag device 20 will be described.

The seatbelt device 24 is a three-point type of seatbelt device. One endof a belt (i.e., a webbing) 28 is wound onto a retractor 26 such that itis able to be unwound therefrom, while another end of the belt 28 isfixed to an anchor 24A. A tongue plate 24T is provided such that it isable to slide along the belt 28, and the vehicle occupant D puts on thebelt 28 by engaging this tongue plate 24T with a buckle 24B. When thebelt 28 is being worn by the vehicle occupant D, it includes a shoulderbelt 28S that fits around an upper body of the vehicle occupant D, and alap belt 28L that extends from the tongue plate 24T to the anchor 24Aand fits around the waist portion of the vehicle occupant D.

In the present exemplary embodiment, the seatbelt device 24 is formed aswhat is known as a ‘seatbelt device with attached seat’ in which theretractor 26, the anchor 24A, and the buckle 24B are provided on thevehicle seat 12. Moreover, in this exemplary embodiment, when operated,the retractor 26 also has a pretensioner function whereby it forciblyretracts the belt 28. Operations of the pretensioner function of theretractor 26 are controlled by an ECU (Electronic Control Unit) 60(described below—see FIG. 4A).

The airbag device 22 is constructed so as to include an inflator 22A anda side airbag 22B, and is housed in a side portion on the outer side inthe vehicle transverse direction of the seat back 16 with the sideairbag 22B in a folded state. When the inflator 22A is operated, itgenerates gas inside the side airbag 22B. According to this structure,this gas causes the side airbag 22B to protrude towards the front fromthe side portion of the seat back 16, and to inflate and deploy on theouter side in the vehicle transverse direction relative to the vehicleoccupant D. In this exemplary embodiment, the side airbag 22B isconstructed such that it is inflated and deployed on the outer side inthe vehicle transverse direction of a pelvic portion P, an abdominalportion A, a breast portion B, and a shoulder portion S of the vehicleoccupant D. Operations of the inflator 22A are also controlled by theECU 60 (described below—see FIG. 4A).

(Multi-directional Airbag Device Structure)

As is shown in FIG. 1 through FIG. 3B, the multi-directional airbagdevice 20 is constructed so as to include a multi-directional airbag 30,which serves as an airbag, an inflator 32, and an airbag case 50. Themulti-directional airbag device 20, which is formed having a modularstructure, is provided on the seat rearward side of the headrest 18above the seat back 16.

The multi-directional airbag 30 is constructed as a single integratedbag body that is inflated and deployed so as to cover the head portion Hof the vehicle occupant D (hereinafter, this will usually be referred tosimply as the ‘head portion H’) from the front and from both the leftand right sides thereof. More specifically, the multi-directional airbag30 is constructed so as to include a pair of left and right frame ducts35 that are inflated and deployed at a distance from each other in anarea that includes both the left and right sides and the top of the headportion H, a forward-deploying portion 36 that deploys in an area thatincludes the front of the head portion H, a pair of side-deployingportions 38 that deploy in an area that includes the both the left andright sides of the head portion H, and an upward-deploying portion 48that deploys in an area that includes the top of the head portion H.

The frame ducts 35 are provided as a pair with one frame duct 35 beingprovided on each side in the seat transverse direction of the headportion H, and are constructed such that each frame duct 35 inflates anddeploys substantially in a U-shape that is open in a downward directionwhen seen in a side view. Specifically, when seen in a side view, in aninflated and deployed state, the frame ducts 35 include a rear duct 35Rthat extends vertically in parallel with the head rest 18, an upper duct35U that extends towards the front from an upper end of the rear duct35R, and a front duct 35F that hangs downwards from a front end of theupper duct 35U.

The forward-deploying portion 36 is constructed so as to include aforward-inflating portion 40 that includes a portion that is deployed tothe front of the head portion H, and non-inflating portions 42 thatdivide the forward-inflating portion 40 into a plurality of inflatingportions. In this exemplary embodiment, the forward-inflating portion 40is constructed so as to include a pair of up-down inflating portions 40Athat are inflated and deployed adjacently to each other in the seattransverse direction such that the longitudinal direction of eachup-down inflating portion 40A is aligned with the up-down direction, anda lower inflating portion 40L that is located underneath the pair ofup-down inflating portions 40A. The pair of up-down inflating portions40A are constructed such that they inflate and deploy at the front(i.e., at a front surface) of the head portion H, while the lowerinflating portion 40L is constructed such that it inflates and deploysat the front of the breast portion B and the shoulder portions S of thevehicle occupant D.

The non-inflating portions 42 are constructed so as to include anon-inflating portion 42A that divides the pair of up-down inflatingportions 40A in the seat transverse direction, and non-inflatingportions 42B that are interposed between the respective up-downinflating portions 40A and the front ducts 35F of the frame duct 35. Inthis exemplary embodiment, the non-inflating portion 42A is formed by alinear seam that extends up and down, while the non-inflating portions42B are each formed as a portion that is surrounded by a toroidal (i.e.,endless) seam that extends up and down.

The side-deploying portions 38 are constructed so as to includeside-inflating portions 44 that, upon being supplied with gas, areinflated and deployed at the sides of the head portion H, andnon-inflating portions 46 that divide the side-inflating portions 44into a plurality of inflating portions. In this exemplary embodiment, inan inflated and deployed state, the side-deploying portions 38 aresurrounded on three sides, namely, the rear, the top, and the front bythe frame duct 35, so as to be formed substantially in a rectangularshape when seen in a side view. The side-deploying portions 38 have asufficiently large size (i.e., surface area) to enable them to wraparound substantially the entire head portion H when seen in a side view.The side-inflating portions 44 of the side-deploying portions 38 arepartitioned from the frame duct 35 by a U-shaped seam 46A which is oneof the seams of the non-inflating portions 46, and which is formed in aninverted U shape that is open towards the bottom. In this exemplaryembodiment, front end sides of the side-inflating portions 44 of theside-deploying portions 38 are connected indirectly to theforward-inflating portion 40 via the front ducts 35F of the frame ducts35.

The non-inflating portions 46 are constructed so as to include a pair offront and rear vertical seams 46B that extend from a bottom edge of theside-inflating portion 44 to an interior of an aperture in the U-shapedseam 46A. The pair of vertical seams 46B are constructed such that theydivide a lower portion 44L of each side-inflating portion 44 into threeinflating portions 44L1, 44L2, and 44L3 that are inflated and deployedadjacently to each other in the front-rear direction. As a result of thelower portion 44L of the side-inflating portions 44 being divided inthis manner into the three inflating portions 44L1 through 44L3, thefront-rear length in a planar cross-sectional view of the lower portion44L of each side-inflating portion 44 in an inflated and deployed stateis made shorter than the front-rear length in a planar cross-sectionalview of the upper portion 44U of each side-inflating portion 44.

In the left and right side-deploying portions 38, when themulti-directional airbag 30 is in an inflated and deployed state, thelower ends 44B of the respective side-inflating portions 44 are incontact with a top of the shoulder portions S of the vehicle occupant D.In this structure, the position in the up-down direction of themulti-directional airbag 30 in an inflated and deployed state relativeto (the head portion H of) the vehicle occupant D is determined by thiscontact of the lower end 44B of each side-deploying portion 44 with theshoulder portions S. The multi-directional airbag 30 is constructed suchthat, when in this positioned state, none of the forward-deployingportion 36, the left and right side deploying portions 38, and theupward-deploying portion 48 (described below) come into contact with thehead portion H of the vehicle occupant D (i.e., such that a gap isformed between them) when the vehicle occupant D is seated in thestandard sitting posture.

The upward-deploying portion 48 is a deployment portion that, with theseat transverse direction taken as the longitudinal direction thereof,inflates and deploys above the head portion H. A seam (not shown in thedrawings), which is a non-inflating portion, is provided in theupward-deploying portion 48, and the thickness in the seat up-downdirection of the upward-deploying portion 48 is restricted by this seam.

The multi-directional airbag device 30 that is constructed in theabove-described manner is formed, as an example, as an integrated bagbody by an OPW (One Piece Woven). As is shown in FIG. 6, themulti-directional airbag 30 is housed in a folded state inside an airbagcase 50 (described below). Specifically, when housed within the airbagcase 50, the multi-directional airbag 30 is constructed so as to includean outward roll-fold portion 30A that is folded in an outwardsroll-fold, and a bellows-fold portion 30B that is folded in a bellowsfold. The outward roll-fold portion 30A is folded into a roll shape thatis rolled up from a front end side of the multi-directional airbag 30when this is in a deployed state towards an outer surface side of theforward-deploying portion 36, and is folded in such a way that, duringinflation and deployment, it is easily able to be deployed towards theseat front side. The bellows-fold portion 30B is located underneath theoutward roll-fold portion 30A, and is constructed such that gas suppliedfrom the inflator 32 flows to the outward roll-fold portion 30A via thebellows-fold portion 30B. Note that it is also possible, for example, toform the multi-directional airbag 30 as an integrated bag body bycutting and sewing peripheral edges of two pieces of woven cloth.

As is shown in FIG. 1, the inflator 32 is provided together with themulti-directional airbag 30 inside the airbag case 50. A combustion-typeor cold gas-type of inflator is employed as the inflator 32, and the gasthat is generated as a result of the inflator 32 being operated issupplied to the interior of the multi-directional airbag 30. Theinflator 32 of the present exemplary embodiment is a cylinder-type ofinflator, and is disposed such that a longitudinal direction thereofextends in the seat transverse direction. Furthermore, as is shown inFIG. 4A, operations of the inflator 32 are controlled by the ECU 60serving as a control device.

(ECU Structure)

The ECU 60 is electrically connected to the retractor 26 of the seatbeltdevice 24, the inflator 22A of the side airbag device 22, and theinflator 32 of the multi-directional airbag device 20. Moreover, the ECU60 is also electrically connected to a collision prediction sensor 62such as a pre-crash sensor and to a collision sensor 64.

Based on signals from the collision prediction sensor 62, the ECU 60 isable to predict whether or not various types of collision areunavoidable for that vehicle. The collision prediction sensor 62 isconstructed, for example, so as to include a stereo camera (not shown inthe drawings) that is provided adjacent to the center in the vehicletransverse direction of an upper portion of the windshield glass. Anarea in the front of the vehicle is photographed by this stereo camera,and objects that may collide with the vehicle are detected. In addition,the distance to a collision object detected by the stereo camera, andthe relative speed between the vehicle and the collision object are alsomeasured, and this measurement data is output to the ECU 60. Based onthis measurement data from the stereo camera, the ECU 60 determineswhether or not a collision with the vehicle is unavoidable. Note that amilliwave radar or the like may be used for the collision predictionsensor 62.

When the ECU 60 has detected a vehicle collision based on a signal fromthe collision sensor 64, it causes a pretensioner mechanism of theretractor 26 to be operated, and also causes the inflator 32 to beoperated. As a consequence, gas generated by the inflator 32 is suppliedto the multi-directional airbag 30. Note that, as an example, thecollision sensor 64 is constructed so as to include a front satellitesensor that is formed by an acceleration sensor that is disposed on afront side member, and a floor sensor that is formed by an accelerationsensor that is disposed on the floor underneath the center console.

(Structure of the Airbag Case 50)

Next, the structure of the airbag case 50 will be described. As is shownin FIG. 5, the airbag case 50 is provided in a seat rear side of aheadrest main body 19 that forms part of the headrest 18. The headrestmain body 19 is disposed at the rear of the head portion H of thevehicle occupant D so as to be able to support the head portion H of thevehicle occupant D from the rear, and is internally provided withcushioning material. The headrest main body 19 is joined via stays 21 tothe seat back 16 (see FIG. 1).

The airbag case 50 which is provided on the seat rear side of theheadrest main body 19 is constructed so as to include a case main body52 and a reaction force plate 54. The case main body 52 is formed fromresin substantially in a box shape, and also functions as a decorativecover for a rear portion of the headrest 18. The case main body 52 isconstructed so as to include a lower wall 52A, a rear wall 52B, and apair of left and right side walls 52C.

The lower wall 52A is located at the same height as a lower surface ofthe headrest main body 19, or alternatively slightly on the seat lowerside of the lower surface of the headrest main body 19, and is disposedsuch that it faces an upper end of the seat back 16. In addition, thelower wall 52A is also formed slightly wider in the seat transversedirection than the headrest main body 19, and both end portions in theseat transverse direction of the lower wall 52A are located on the outerside in the seat transverse direction of the headrest main body 19.

The rear wall 52B extends towards the seat upper side from a rear endportion of the lower wall 52A, and in a side view looking from the seattransverse direction, slopes gradually towards the rear as it moves fromthe upper side towards the lower side. Moreover, a top end of the rearwall 52B curves towards the headrest main body 19 (see FIG. 6).

The pair of left and right side walls 52C extend towards the seat upperside from both end portions in the seat transverse direction of thelower wall 52A, and this pair of side walls 52C are disposed facing eachother in the seat transverse direction. Rear edges of each of the pairof side walls 52C are joined respectively to the rear wall 52B, and in aside view looking from the seat transverse direction, are formed suchthat they slope gradually towards the rear as they move from the upperside towards the lower side.

As is described above, the case main body 52 is formed substantially ina box shape that is open on the seat forward side, and a space isprovided between the case main body 52 and the headrest main body 19where the multi-directional airbag 30 is housed. Moreover, as is shownin FIG. 4B, the aperture on the seat front side of the case main body 52is closed off by an airbag door 33. In the present exemplary embodiment,when seen in a front view, the space between the airbag case 50 and theheadrest main body 19 is closed off by the airbag door 33, and astructure is employed in which, triggered by a tear line 33A, the airbagdoor 33 is split open by inflation pressure from the multi-directionalairbag 30 so that the multi-directional airbag 30 is allowed to inflateand deploy towards the front.

As is shown in FIG. 5, the case main body 52 is formed from resin as asingle body, and the reaction force plate 54 is formed integrally withthe case main body 52 on the lower portion side thereof. The reactionforce plate 54 is formed by a component having greater rigidity than thecase main body 52, and in the present exemplary embodiment, as anexample, is made from metal. The reaction force plate 54 is formedintegrally with the case main body 52 by being insert-molded inside thecase main body 52. The reaction force plate 54 is constructed so as toinclude a lower wall reinforcement portion 54A, side wall reinforcementportions 54C, and a rear wall reinforcement portion 54B.

The lower wall reinforcement portion 54A is disposed inside the lowerwall 52A of the case main body 52, and is formed slightly smaller thanthe lower wall 52A. The rigidity of the lower surface of the airbag case50 is increased by this lower wall reinforcement portion 54A.

The rear wall reinforcement portion 54B extends from a rear end of thelower wall reinforcement portion 54A in parallel with the rear wall 52Bof the case main body 52 towards the seat upper side, and is disposedinside the rear wall 52B. A top end portion of the rear wallreinforcement portion 54B is located slightly on the seat upper side ofan intermediate portion in the seat up-down direction of the rear wall52B, and the rear wall reinforcement portion 54B does not extend as faras the upper portion of the rear wall 52B. The rigidity of the lowerportion side of the rear surface of the airbag case 50 is increased bythis rear wall reinforcement portion 54B.

The side wall reinforcement portions 54C extend from both sides in theseat transverse direction of the rear wall reinforcement portion 54B inparallel with the side walls 52C of the case main body 52 towards theseat front side, and are disposed inside the side walls 52C of the casemain body 52. Lower ends of the side wall reinforcement portions 54C arejoined to the lower wall reinforcement portion 54A. Furthermore, seatfront sides of the side wall reinforcement portions 54C either slope orare curved such that, when viewed from the seat transverse direction, alower portion thereof is located closer to the seat front side than anupper portion thereof. The seat front sides of the side wallreinforcement portions 54C of the present exemplary embodiment arecurved such that a lower portion thereof is located closer to the seatfront than an upper portion thereof. Because of this, the side wallreinforcement portions 54C are formed in a substantially triangularshape in which, when viewed from the seat transverse direction, a cornerportion on the front portion side and the top portion side of therectangle is cut away towards the inner side. Moreover, as is shown inFIG. 6, the side wall reinforcement portions 54C are formed in a shapein which, when viewed from the seat transverse direction, they avoid theoutward roll-fold portion 30A of the multi-directional airbag 30. Inother words, the outward roll-fold portion 30A is housed in a positionwhere it does not overlap with the side wall reinforcement portions 54Cwhen viewed from the seat transverse direction.

The rigidity of the lower portion side of the case main body 52 isincreased by the reaction force plate 54 which is constructed in themanner described above. Moreover, as is shown in FIG. 7, during theinflation and deployment of the multi-directional airbag 30, the upperportion of the airbag case 50 where the reaction force plate 54 is notprovided is opened up by inflation pressure, and is deformed towards theseat rear side. As a consequence, a structure is created in which themulti-directional airbag 30 is deployed towards the seat front side.

(Operation and Effects)

Next, an operation of the exemplary embodiment will be described.

In the vehicle occupant protection device 10 of the present exemplaryembodiment, the metal reaction force plate 54 is provided on the lowerportion side of the case main body 52 of the airbag case 50, and therigidity of the lower portion side of the case main body 52 is increasedby this reaction force plate 54. As a consequence, when the upperportion of the airbag case 50 is opened by the inflation pressure of themulti-directional airbag 30, it is possible to prevent the lower portionside of the case main body 52 from deforming towards the seat rear side.In addition, because the multi-directional airbag 30 is supported fromthe seat rear side by the rear wall reinforcement portion 54B of thisreaction force plate 54, reaction force towards the seat front side isapplied to the multi-directional airbag 30 from the rear wallreinforcement portion 54B. As a result, it is easy to make themulti-directional airbag 30 inflate and deploy towards the seat frontside from the upper portion of the case main body 52. Namely, thedeployment performance of the multi-directional airbag 30 can beimproved.

Moreover, in the present exemplary embodiment, as is shown in FIG. 5,the side wall reinforcement portions 54C extend towards the seat frontside in parallel with the side walls 52C of the case main body 52 fromboth sides in the seat transverse direction of the rear wallreinforcement portion 54B of the reaction force plate 54. As aconsequence of this, it is possible to increase the flexural rigiditytowards the seat rear side of the rear wall reinforcement portion 54 ofthe reaction force plate 54, and it is possible to prevent the lowerportion of the rear surface of the airbag case 50 from deforming towardsthe rear side during the inflation and deployment of themulti-directional airbag 30. Moreover, the side wall reinforcementportions 54C either slope or are curved such that, when viewed from theseat transverse direction, a lower portion thereof is located closer tothe seat front side than an upper portion thereof. As a consequence,compared with a structure in which the side wall reinforcement portions54C are formed in a rectangular shape when viewed from the seattransverse direction, it is possible to reduce the surface area of theside wall reinforcement portions 54C, and to prevent the reaction forceplate 54 from interfering with the multi-directional airbag 30 when thisis inflated and deployed in the seat transverse direction from the casemain body 52. In this manner, it is possible to prevent the inflationand deployment of the multi-directional airbag 30 being obstructed inthe seat transverse direction and, at the same time, to increasereaction force applied to the multi-directional airbag 30.

Furthermore, in the present exemplary embodiment, because the outwardroll-fold portion 30A is housed in a position where it does not overlapwith the side wall reinforcement portions 54C of the reaction forceplate 54 when viewed from the seat transverse direction, it is possibleto prevent the inflation and deployment of at least the outwardroll-fold portion 30A from being obstructed by the side wallreinforcement portions 54C. Moreover, the bellows-fold portion 30B isprovided underneath the outward roll-fold portion 30A, and gas generatedfrom the inflator 32 is supplied to the outward roll-fold portion 30Avia the bellows-fold portion 30B. As a consequence, because thebellow-fold portion 30B is inflated and deployed before the outwardroll-fold portion 30A, the outward roll-fold portion 30A is pushedupwards, and the outward roll-fold portion 30A can be rapidly inflatedand deployed towards the seat front side of the headrest main body 19.

Furthermore, in the present exemplary embodiment, the multi-directionalairbag 30 is constructed as an integrated bag body that is deployed inan area that includes the front side of the head portion H of thevehicle occupant D, and in an area that incudes both the left and rightsides thereof so as to cover the head portion H of the vehicle occupantD. As a consequence, in the event of a vehicle collision, because thehead portion H of the vehicle occupant D is covered by themulti-directional airbag 30, it is possible to restrain and protect thehead portion H of the vehicle occupant D in various different types ofcollision.

Moreover, in the present exemplary embodiment, the multi-directionalairbag 30 is housed in the airbag case 50 which is provided on the seatrear side of the headrest main body 19. Because of this, compared with astructure in which, for example, a gas supply pipe that is disposed soas to surround the head portion H of the vehicle occupant D from aboveprotrudes at all times into the vehicle cabin interior, it is possibleto improve the pre-operating appearance, while guaranteeing a level ofvehicle occupant protection equal to or surpassing that provided by theabove structure. Moreover, adjustment of the front-rear position,adjustment of the height, and reclining operations and the like of thevehicle seat 12 are not obstructed by the multi-directional airbagdevice 20.

The vehicle occupant protection device 10 according to an exemplaryembodiment of the present invention has been described above, however,it is to be understood that the present invention may be implemented ina variety of forms insofar as they do not depart from the spirit orscope of the present invention. For example, as is shown in FIG. 5, thereaction force plate 54 of the present exemplary embodiment isconstructed so as to include the lower wall reinforcement portion 54A,the rear wall reinforcement portion 54B, and the side wall reinforcementportions 54C, however, the present invention is not limited to this. Itis also possible for the reaction force plate 54 to be formed by onlythe lower wall reinforcement portion 54A and the rear wall reinforcementportion 54B. In this case, the side walls 52C of the case main body 52may also be formed by resin components having a high degree of rigidity.Moreover, the reaction force plate 54 may also be formed by only therear wall reinforcement portion 54B and the side wall reinforcementportions 54C.

Moreover, in the present exemplary embodiment, the seat front side ofeach side wall reinforcement portion 54C is curved such that a lowerportion thereof is located closer to the seat front than an upperportion thereof when viewed from the seat transverse direction, however,the present invention is not limited to this. For example, it is alsopossible to employ a structure in which the seat front side of each sidewall reinforcement portion 54C slopes such that, when viewed from theseat transverse direction, a lower portion thereof is located closer tothe seat front than an upper portion thereof. In this case as well,compared with a structure in which, when viewed from the seat transversedirection, rectangular-shaped side wall reinforcement portions areprovided, it is possible to prevent the multi-directional airbag 30being obstructed by the side wall reinforcement portions 54C duringinflation and deployment.

Furthermore, from the standpoint of hastening the inflation anddeployment of the multi-directional airbag 30, it is also possible toemploy a structure in which, when the outward roll-fold portion 30A ishoused, it is positioned on the front side of the inside of the airbagcase 50 so that, when viewed from the seat transverse direction, theoutward roll-fold portion 30A and the side wall portions 54C do notoverlap with each other. For example, if a positioning component such asa urethane pad or the like is disposed in a rear portion of the insideof the airbag case 50, then the outward roll-fold portion 30A can bepositioned on the front side of the inside of the airbag case 50. As aconsequence, it is possible to prevent the outward roll-fold portion 30Afrom moving to the rearward side of the inside of the airbag case 50because of vibrations or the like while the vehicle is traveling, andthe outward roll-fold portion 30A can be effectively prevented fromoverlapping with the side wall reinforcement portions 54C when viewedfrom the seat transverse direction.

Moreover, in the present exemplary embodiment, the reaction force plate54 and the case main body 52 are formed as a single integral body viainsert molding, however, the present invented is not limited to this.For example, it is also possible to firstly form the case main body 52using a resin mold, and to thereafter assemble the reaction force plate54 together with the case main body 52. Furthermore, the reaction forceplate 54 is formed from metal, however, the present invention is notlimited to this, and provided that the reaction force plate 54 hasgreater rigidity than the case main body 52, then the reaction forceplate 54 may be formed from another material. For example, it is alsopossible to form the reaction force plate 54 from fiber-reinforced resinthat has been reinforced with glass fibers or the like, or fromreinforced resin that has been reinforced with talc (i.e., with finelyground talcum powder). In this case as well, because the rigidity of thelower portion side of the case main body 52 is increased by the reactionforce plate 54, this structure has the effect of causing a reactionforce towards the seat front side to act on the multi-directional airbag30 during inflation and deployment.

Furthermore, in the present exemplary embodiment, a design surface isformed on the rear portion of the headrest 18 by the airbag case 50,however, the present invention is not limited to this. For example, itis also possible to create a sense of harmony by covering the airbagcase 50 and the headrest main body 19 with upholstery.

Moreover, in the present exemplary embodiment, the headrest 18 and theseat back 16 are joined together by the stays 21, however, the presentinvention is not limited to this. It is also possible for the headrest18 and the seat back 16 to be formed as an integrated structure. In thiscase, the portion thereof that is constructed such that it is able tosupport the head portion H of the vehicle occupant D from the rearcorresponds to the ‘headrest main body’ of the present invention.

Moreover, in the above-described exemplary embodiment, the inflator 32is disposed inside the airbag case 50, however, the present invention isnot limited to this. For example, it is also possible to dispose theinflator 32 inside the upper portion of the seat back 16. Moreover, thenumber and placement of the inflators 32 are not limited and it ispossible, for example to dispose inflators 32 vertically inside the seatback 16 such that the longitudinal direction thereof is aligned with theseat up-down direction.

Furthermore, the present invention is not limited to a structure inwhich the seatbelt device 24 is provided in the vehicle seat 12, and itis also possible to employ a structure in which the retractor 26, anchor24A, buckle 24B and the like are provided on the vehicle body. Moreover,in a structure in which the vehicle occupant protection device 10 isprovided with the seatbelt device 24, then the seatbelt device 24 is notlimited to being a three-point type of device, and may also be afour-point type of seatbelt device or the like.

Moreover, in the present exemplary embodiment, an example is describedin which the vehicle seat 12 is disposed such that the seat transversedirection matches the vehicle transverse direction, however, the presentinvention is not limited to this. For example, the vehicle seat 12 mayalso be disposed diagonally relative to the vehicle body, or may beconstructed such that the orientation thereof relative to the vehiclebody is able to be altered (by being rotated around a vertical axis).Because the multi-directional airbag 30 is inflated and deployed suchthat it covers the head portion H of the vehicle occupant D even if thistype of structure is employed, this can also contribute to the superiorprotection of the head portion H. Moreover, because themulti-directional airbag 30 is housed in the headrest 18, it isdifficult for there to be any interference between the multi-directionalairbag 30 and the vehicle cabin interior surfaces or vehicle cabininterior components, and any impediment to the operation to alter theorientation of the vehicle seat 12 relative to the vehicle body can besuppressed or prevented.

What is claimed is:
 1. A vehicle occupant protection device comprising:an airbag that is inflated and deployed upon being supplied with gas,and that is constructed as an integrated bag body that is deployable inan area that includes a front side of a head portion of a vehicleoccupant, and in an area that includes both left and right sides of thehead portion of the vehicle occupant so as to cover the head portion;and an airbag case that is constructed so as to include a box-shapedcase main body that is provided on a seat rear side of a headrest mainbody that supports the head portion from the rear, and in which theairbag is housed in a folded state, and that inflates and deploys theairbag from an upper portion of the case main body during an inflationand deployment of the airbag, and a reaction force plate that isprovided in a lower portion side of the case main body and inside thecase main body, and that supports the airbag from the seat rear sideduring the inflation and deployment of the airbag.
 2. The vehicleoccupant protection device according to claim 1, wherein the case mainbody is formed from resin, and the upper portion of the case main bodyopens up during the inflation and deployment of the airbag.
 3. Thevehicle occupant protection device according to claim 1, wherein thereaction force plate is formed by a component having greater rigiditythan that of the case main body.
 4. The vehicle occupant protectiondevice according to claim 1, wherein the case main body is formed fromresin substantially in a box shape, and also functions as a decorativecover for a rear portion of the headrest main body.
 5. The vehicleoccupant protection device according to claim 1, wherein the case mainbody is formed substantially in a box shape that is open on a seatforward side.
 6. The vehicle occupant protection device according toclaim 1, wherein the reaction force plate is made from metal, and isformed integrally with the case main body by being insert-molded insidethe case main body.
 7. The vehicle occupant protection device accordingto claim 1, wherein: the reaction force plate is provided with a rearwall reinforcement portion that is disposed in parallel with a rear wallof the case main body, and with side wall reinforcement portions thatextend towards a seat front side in parallel with side walls of the casemain body from both sides in a seat transverse direction of the rearwall reinforcement portion, and a top end portion of the rear wallreinforcement portion is located on a seat upper side of a centralportion in a seat up-down direction of the rear wall, and the rear wallreinforcement portion does not extend as far as an upper portion of therear wall.
 8. The vehicle occupant protection device according to claim1, wherein: an inflator is provided together with the airbag inside theairbag case, and the inflator is a cylinder-type inflator, and isdisposed such that a longitudinal direction thereof extends in a seattransverse direction.
 9. The vehicle occupant protection deviceaccording to claim 1, wherein: the airbag includes an outward roll-foldportion that is housed in the case main body in a folded state that isrolled up from a front end side of the airbag, when the airbag is in adeployed state, towards an outer surface side, and a bellows-foldportion that is housed in the case main body in a folded state in abellows fold underneath the outward roll-fold portion, and the airbag isconfigured such that gas supplied from an inflator flows to the outwardroll-fold portion via the bellows-fold portion.